Polyhydroxyl compounds containing acyl urea groups useful in preparation of polyurethane foams

ABSTRACT

This invention relates to new polyols modified by acyl urea groups, to a process for the preparation thereof and to the use thereof as starting component for the preparation of preferably foamed polyurethane plastics. The process involves (A) reacting diisocyanatocarbodiimides corresponding to the following general formula: 
     
         OCN--R.sup.2 --N═C═N).sub.m R.sup.2 --NCO 
    
     at a temperature of from about 25° to 130° C., optionally in the presence of an inert solvent, with polyhydroxyl compounds corresponding to the following general formula: 
     
         A--OH).sub.n 
    
     in an OH/NCO-ratio of from 1.2:1 to 30:1 to form a polyhydroxyl compound containing carbodiimide groups and (B) completely or partially reacting, the carbodiimide groups remaining in the product of step (A) at a temperature of from 25° to 100° C., optionally in the presence of an inert solvent, with a carboxylic acid corresponding to the following general formula: ##STR1## TO FORM ACYL UREA GROUPS, AND (C) distilling off the inert solvent, if used; wherein 
     M represents a number of from 1 to 10; 
     S represents an integer of from 1 to 3; and 
     R 1  represents hydrogen or a monofunctional or -- in the form of a bridge to further acyl groups -- a di- or trifunctional C 1  -C 18  aliphatic, C 4  -C 15  cycloaliphatic, C 6  -C 15  araliphatic or aromatic radical which may contain one or two double bonds and/or be branched and which may optionally contain one or two substituents selected from the group consisting of hydroxyl, mercapto, secondary amino, sulphonic acid ester, phosphonic acid ester, carboxylic ester, siloxane or trifluoromethyl groups, fluorine, chlorine, bromine or iodine; 
     R 2  represents a difunctional aliphatic, cycloaliphatic, aromatic or araliphatic radical containing from 4 to 25 carbon atoms obtained by removing the isocyanate groups from a diisocyanate; 
     A represents an n-functional radical obtained by removing the hydroxyl groups from a polyhydroxyl compound having a molecular weight of from 62 to 6000; 
     X and Y, which may be the same or different, each represents oxygen or sulphur; 
     N represents an integer of from 2 to 8.

BACKGROUND OF THE INVENTION

The idea of producing acyl urea modified polyisocyanates fromcarbodiimide modified polyisocyanates is known e.g. U.S. Pat. Nos.3,517,039; 3,383,400; and 3,914,269. However, the idea of producing acylurea modified polyols is heretofore unknown.

DESCRIPTION OF THE INVENTION

More particularly, the present invention relates to compounds containingat least two, preferably from 2 to 8 and, with particular preference,from 2 to 4, terminal hydroxyl groups, having a molecular weight of from400 to 20,000, preferably from 600 to 15,000 and, with particularpreference, from 2000 to 10,000 and comprising segments corresponding tothe following general formulae: ##STR2## wherein X and Y, which may bethe same or different, each represents oxygen or sulphur, preferablyoxygen;

R¹ represents hydrogen or a monofunctional or, in the form of a bridgeto other acyl urea groups, di- or trifunctional (preferablydifunctional) C₁ -C₁₈, preferably C₁ -C₆, aliphatic; C₄ -C₁₅, preferablyC₆ -C₁₀, cycloaliphatic; C₆ -C₁₅, preferably C₆ -C₁₀, araliphatic oraromatic radical which may optionally contain one or two double bondsand/or be branched and which may optionally contain one or two of thefollowing substituents: hydroxyl, mercapto, secondary amino, sulphonicacid ester, phosphoric acid ester, carboxylic, carboxylic ester,siloxane or trifluoromethyl groups, fluorine, chlorine, bromine oriodine;

R² represents a difunctional aliphatic, cycloaliphatic, aromatic oraraliphatic radical having from 4 to 25, preferably from 6 to 15, carbonatoms of the type obtained by removing the isocyanate groups from adiisocyanate;

A represents an n-functional radical of the type obtained by removingthe hydroxyl groups from a polyhydroxyl compound having a molecularweight of from 62 to 6000;

n represents an integer of from 2 to 8, preferably from 2 to 4 and, withparticular preference, 2 or 3; and

z represents an integer having a value of from 0 to (n-1).

The present invention also relates to a process for the preparation ofthe polyhydroxyl compounds containing acyl urea groups, wherein, in afirst step, diisocyanatocarbodiimides corresponding to the followinggeneral formula:

    OCN--R.sup.2 --N═C═N).sub.m R.sup.2 --NCO

are reacted at a temperature of from about 25° to 130° C., preferablyfrom 90° to 120° C., optionally in the presence of an inert solvent,with polyhydroxyl compounds corresponding to the following generalformula:

    A--OH).sub.n

in an OH/NCO-ratio of from 1.2:1 to 30:1, preferably from 1.5:1 to 15:1and, with particular preference, about 2:1, to form a polyhydroxylcompound containing carbodiimide groups. In a second step, thecarbodiimide groups are completely or only partly reacted at atemperature of from 25 to 100° C., preferably from 60° to 90° C.,optionally in the presence of an inert solvent, with a carboxylic acidcorresponding to the following general formula: ##STR3## to form acylurea groups. After the reaction, the solvent if used, is distilled off.In the above process,

m represents a number of from 1 to 10, preferably 1 or 2; and

s represents an integer of from 1 to 3, preferably 1 or 2; and

R¹, r², a, x, y and n are as defined above.

The preparation of diisocyanatocarbodiimides corresponding to thefollowing general formula:

    OCN--R.sup.2 --N═C═N).sub.m R.sup.2 --NCO

is known and is described, for example, in U.S. Pat. Nos. 2,840,589 and2,941,966 and by P. W. Campbell and K. C. Smeltz in "Journal of OrganicChemistry", 28, 2069 (1963). Diisocyanatocarbodiimides may also beobtained in a particularly mild manner and free from secondary productsby heterogeneous catalysis in accordance with GermanOffenlegungsschriften Nos. 2,504,400 and 2,552,350. The conversion ofdiisocyanates into carbodiimides in the presence of very smallquantities of phospholine oxide, followed by blocking of the catalystwith acid chlorides, is described in DOS No. 2,653,120.

Starting components suitable for producing the diisocyanatocarbodiimidesare aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclicpolyisocyanates of the type described, for example, by W. Siefken inJustus Liebigs Annalen der Chemie, 562, pages 75 to 136. These include,for example, ethylene diisocyanate; 1,4-tetramethylene diisocyanate;1,6-hexamethylene diisocyanate; 1,12-dodecane diisocyanate;cyclobutane-1,3-diisocyanate; cyclohexane-1,3- and -1,4-diisocyanate andmixtures of these isomers;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane (DAS No.1,202,785; U.S. Pat. No. 3,401,190), 2,4- and 2,6-hexahydrotolylenediisocyanate and mixtures of these isomers; hexahydro-1,3- and/or-1,4-phenylene diisocyanate; perhydro-2,4'- and/or -4,4'-diphenylmethane diisocyanate; 1,3- and 1,4-phenylene diisocyanate; 2,4- and2,6-tolylene diisocyanate and mixtures of these isomers; diphenylmethane-2,4'- and/or -4,4'-diisocyanate; naphthylene-1,5-diisocyanate;m- and p-isocyanatophenyl sulphonyl isocyanates according to U.S. Pat.No. 3,454,606; perchlorinated aryl polyisocyanates of the typedescribed, for example, in German Auslegeschrift No. 1,157,601 (U.S.Pat. No. 3,277,138); polyisocyanates containing carbodiimide groups ofthe type described in German Pat. No. 1,092,007 (U.S. Pat. No.3,152,162); diisocyanates of the type described in U.S. Pat. No.3,492,330; polyisocyanates containing allophanate groups of the typedescribed, for example, in British Pat. No. 994,890, in Belgian Pat. No.761,626 and in Published Dutch Pat. application No. 7,102,524;polyisocyanates containing isocyanurate groups of the type described,for example, in U.S. Pat. No. 3,001,973, in German Pat. Nos. 1,022,789;1,222,067 and 1,027,394 and in German Offenlegungsschriften Nos.1,929,034 and 2,004,048; polyisocyanates containing urethane groups ofthe type described, for example, in Belgian Pat. No. 752,261 or in U.S.Pat. No. 3,394,164; polyisocyanates containing acylated urea groupsaccording to German Pat. No. 1,230,778; polyisocyanates containingbiuret groups of the type described, for example, in German Pat. No.1,101,394 (U.S. Pat. Nos. 3,124,605 and 3,201,372) and in British Pat.No. 889,050; polyisocyanates produced by telomerization reactions of thetype described, for example, in U.S. Pat. No. 3,654,106; polyisocyanatescontaining ester groups of the type described, for example, in BritishPat. Nos. 965,474 and 1,072,956, in U.S. Pat. No. 3,567,763 and inGerman Pat. No. 1,231,688; reaction products of the above-mentionedisocyanates with acetals according to German Pat. No. 1,072,385 andpolyisocyanates containing polymeric fatty acid residues according toU.S. Pat. No. 3,455,883.

It is particularly preferred to use diisocyanates of the type in whichone isocyanate group has a greater tendency towards carbodiimideformation than the other. Examples of such diisocyanates include:2,4-tolylene diisocyanate; 1-methoxy-2,4-phenylene diisocyanate;1-chlorophenyl-2,4-diisocyanate; p-(1-isocyanatoethyl)-phenylisocyanate; m-(3-isocyanatobutyl)-phenyl isocyanate and4-(2-isocyanatocyclohexyl-methyl)-phenyl isocyanate.

According to the present invention, polyhydroxyl compounds correspondingto the following general formula:

    A--OH).sub.n

include, on the one hand, polyhydric alcohols having a molecular weightof from 62 to approximately 250 and, on the other hand, polyester andpolyether polyols having a molecular weight of from 150 to 6000,preferably from 500 to 5000 and, with particular preference, from 1000to 4000, of the type known for the preparation of homogeneous andcellular polyurethane plastics.

Examples of such compounds include: ethylene glycol; 1,2- and1,3-propylene glycol; 1,4- and 2,3-butylene glycol; 1,5-pentane diol;1,6-hexane diol; 1,8-octane diol; neopentyl glycol;1,4-bis-hydroxymethyl cyclohexane; 2-methyl-1,3-propane diol; glycerol;trimethylol propane; 1,2,6-hexane triol; trimethylol ethane;pentaerythritol; quinitol; mannitol; sorbitol; diethylene glycol;triethylene glycol; tetraethylene glycol; polyethylene glycols having amolecular weight of up to 400; dipropylene glycol; polypropylene glycolshaving a molecular weight of up to 400; dibutylene glycol; polybutyleneglycols having a molecular weight of up to 400; methyl glycoside;diethanolamino-N-methyl phosphonic acid ester; castor oil;diethanolamine; N-methyl ethanolamine; and triethanolamine.

Suitable polyesters containing hydroxyl groups include, for example,reaction products of polyhydric, preferably dihydric acid, optionally,even trihydric alcohols with polybasic, preferably dibasic, carboxylicacids. Instead of using the free polycarboxylic acids, it is alsopossible to use the corresponding polycarboxylic acid anhydrides orcorresponding polycarboxylic acid esters of lower alcohols or mixturesthereof for producing the polyesters. The polycarboxylic acids may bealiphatic, cycloaliphatic, aromatic and/or heterocyclic and mayoptionally be substituted, for example, by halogen atoms, and/or may beunsaturated.

Examples of such polycarboxylic acids include: succinic acid, adipicacid, suberic acid, azelaic acid, sebacic acid, phthalic acid,isophthalic acid, trimellitic acid, phthalic acid anhydride,tetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride,tetrachlorophthalic acid anhydride, endomethylene tetrahydrophthalicacid anhydride, glutaric acid anhydride, maleic acid, maleic acidanhydride, fumeric acid, dimeric and trimeric fatty acids, such as oleicacid, optionally in admixture with monomeric fatty acids, terephthalicacid dimethyl ester and terephthalic acid-bis-glycol ester. Suitablepolyhydric alcohols include, for example, ethylene glycol; 1,2- and1,3-propylene glycol; 1,4- and 2,3-butylene glycol; 1,6-hexane diol;1,8-octane diol; neopentyl glycol; cyclohexane dimethanol(1,4-bis-hydroxymethylcyclohexane); 2-methyl-1,3-propane diol; glycerol;trimethylol propane; 1,2,6-hexane triol; 1,2,4-butane triol; trimethylolethane; pentaerythritol, quinitol; mannitol; sorbitol; methyl glycoside,diethylene glycol; triethylene glycol; tetraethylene glycol;polyethylene glycols; dipropylene glycol; polypropylene glycols;dibutylene glycol and polybutylene glycols. (The polyesters may alsocontain terminal carboxyl groups. Polyesters of lactones, for example,ε-caprolactone, or hydroxy carboxylic acids, for exampleω-hydroxycaproic acid, may also be used.)

The polyethers containing at least two, generally from two to eight,preferably 2 or 3, hydroxyl groups which may be used in accordance withthe present invention are also known and are obtained, for example, bypolymerizing epoxides, such as ethylene oxide, propylene oxide, butyleneoxide, tetrahydrofuran, styrene oxide or epichlorhydrin, on their own,for example in the presence of BF₃, or by adding these epoxides,optionally in admixture or successively, with starter componentscontaining reactive hydrogen atoms. Such starter compounds includewater, ammonia, alcohols or amines, for example ethylene glycol, 1,3- or1,2-propylene glycol, trimethylol propane, 4,4'-dihydroxydiphenylpropane, aniline, ethanolamine or ethylene diamine. Sucrose polyethersof the type described for example, in German Auslegeschriften No.1,176,358 and 1,064,938 may also be used in accordance with the presentinvention. In many cases, it is preferred to use polyethers of the typewhich predominantly contain primary OH-groups (up to 90%, by weight,based on all the OH-groups present in the polyether). Polyethersmodified by vinyl polymers of the type obtained, for example, bypolymerizing styrene and acrylonitrile in the presence of polyethers(U.S. Pat. Nos. 3,383,351; 3,304,273; 3,523,093 and 3,110,695; GermanPat. No. 1,152,536) are also suitable, as are polybutadienes containingOH-groups.

Among the polythioethers, particular reference is made to thecondensation products of thiodiglycol on its own and/or with otherglycols, dicarboxylic acids, formaldehyde, aminocarboxylic acids oramino alcohols. Depending upon the co-components, the products arepolythio mixed ethers, polythioether esters or polythioether esteramides.

Suitable polyacetals are, for example, the compounds obtainable from thereaction of glycols, such as diethylene glycol, triethylene glycol,4,4'-dioxethoxy diphenyl dimethyl methane and hexane diol, withformaldehyde. Polyacetals suitable for use in accordance with thepresent invention may also be obtained by the polymerization of cyclicacetals.

Polycarbonates containing hydroxyl groups suitable for use in accordancewith the present invention are those known compounds which may beprepared, for example, by reacting diols, such as 1,3-propane diol,1,4-butane diol and/or 1,6-hexane diol, diethylene glycol, triethyleneglycol or tetraethylene glycol, with diaryl carbonates, for examplediphenyl carbonate, or with phosgene.

The polyester amides and polyamides include, for example, thepredominantly linear condensates obtained from polybasic saturated andunsaturated carboxylic acids or the anhydrides thereof andpolyfunctional saturated and unsaturated amino alcohols, diamines,polyamines and mixtures thereof.

Polyhydroxyl compounds already containing urethane or urea groups andoptionally modified natural polyols, such as castor oil, carbohydratesor starch, may also be used. Addition products of alkylene oxides withphenol-formaldehyde resins or even with urea-formaldehyde resins mayalso be used in accordance with the present invention.

Representatives of these compounds which may be used in accordance withthe present invention are described, for example, in High Polymers, Vol.XVI, "Polyurethanes, Chemistry and Technology", by Saunders-Frisch,Interscience Publishers, New York, London, Vol. I, 1962, pages 32 to 42and pages 44 to 54 and Vol. II, 1964, pages 5-6 and 198-199, and inKunststoff-Handbuch, Vol. VII, Vieweg-Hochtlen, Carl-Hanser Verlag,Munich, 1966, for example on pages 45 to 71.

According to the present invention, however, it is also possible to usepolyhydroxyl compounds which contain high molecular weight polyadductsor polycondensates in finely disperse or dissolved form. Such modifiedpolyhydroxyl compounds are obtained by carrying out polyadditionreactions (for example reactions between polyisocyanates andamino-functional compounds) or polycondensation reactions (for examplebetween formaldehyde and phenols and/or amines) in situ in theabove-mentioned compounds containing hydroxyl groups. Such processes aredescribed, for example, in German Auslegeschriften Nos. 1,168,075 and1,260,142 and in German Offenlegungsschriften Nos. 2,324,134; 2,423,984;2,512,385; 2,513,815; 2,550,796; 2,550,797; 2,550,833 and 2,550,862.However, it is also possible, in accordance with U.S. Pat. No. 3,869,413or German Offenlegungsschrift No. 2,550,860, to mix a prepared aqueouspolymer dispersion with a polyhydroxyl compound and then to remove thewater from the mixture.

According to the present invention, preferred polyols are polypropyleneglycols, trimethylol propane- or glycerol-started copolymers ofpropylene oxide and ethylene oxide and also polyesters based on adipicacid, 1,4-butane diol, diethylene glycol, 1,6-hexane diol and/orneopentyl glycol.

In the first step of the process according to the present invention, thediisocyanatocarbodiimides corresponding to the following generalformula:

    OCN--R.sup.2 --N═C═N).sub.m R.sup.2 --NCO

are reacted with the polyhydroxyl compounds corresponding to thefollowing general formula:

    A--OH).sub.n

in an OH/NCO-ratio of from 1.2:1 to 30:1, preferably from 1.5:1 to 15:1and, with particular preference, about 2:1, at temperatures of from 25°to 130° C., preferably from 90° to 120° C. The progress of the reactionmay readily be followed by IR-spectroscopy from the disappearance of theisocyanate band at 2220 cm⁻¹.

After all the isocyanate groups have reacted, a mono-, di- ortricarboxylic acid corresponding to the following general formula:##STR4## is added at a temperature of from 25° to 100° C., preferablyfrom 60° to 90° C. A quantity of carboxylic acid groups substantiallyequivalent to the carbodiimide groups is preferably used. However, it isalso possible, in order to retain some of the carbodiimide groups, toadd a less than equivalent amount of carboxylic acid (from about 25 to95% of the equivalent quantity). The free carbodiimide groups which arestill present in that case may optionally be reacted with otherreactants, for example with amines or water. In the case ofpolycarboxylic acids, it is also possible to use more than equivalentquantities. In that case, modified polyols containing free carboxygroups are formed.

In the above general formula, R¹ preferably represents a C₁ -C₁₇aliphatic hydrocarbon radical which may optionally contain double bondsand/or branches and which may be substituted by chlorine, hydroxylgroups or secondary alkylamino groups.

Examples of suitable carboxylic acids include: formic acid, acetic acid,thioacetic acid, propionic acid, pivalic acid lactic acid, lauric acid,stearic acid, acrylic acid, methacrylic acid, oleic acid, undecylenicacid, sorbic acid, linoleic acid, crotonic acid, cyclohexane carboxylicacid, 1-cyclohexane carboxylic acid, caproic acid, chloroacetic acid,phenoxy acetic acid, 2-chlorophenoxy acetic acid,N,N-dimethyl-6-aminocaproic acid, linolenic acid, adipic, sebacic acid,dimethylol propionic acid, citric acid and salicylic acid.

The process according to the present invention may optionally be carriedout in the presence of inert solvents, for example benzene, toluene,xylene, chlorobenzene, dichlorobenzene and mixtures thereof withsterically hindered alcohols, such as tert.-butanol; methylene chloride,chloroform, dimethyl formamide or dioxane. In order to isolate the pureproduct, the solvent used, if any, may be subsequently removed.

It is known from the literature that carbodiimides react with alcoholsto form isourea compounds. Accordingly, it may be regarded as surprisingthat virtually no addition of hydroxyl groups with the carbodiimidegroups to form cross-linked, insoluble products occurs in the first stepof the process according to the present invention. Instead, anintermediate product which is relatively stable in storage is formed. Itmay also be regarded as surprising that, in the second step of theprocess according to the present invention, there is no ester formationbetween the carboxylic acid and the free hydroxyl groups because it alsois known from the literature that carbodiimides greatly accelerate theesterification reaction. The fact that virtually no esterificationoccurs in the process according to the present invention is proved bythe absence of the urea band at 1675 cm⁻¹ in the IR-spectrum of the endproduct. After an esterification reaction, such a band should appearautomatically through the addition of water with the carbodiimide group.

The modified polyhydroxyl compounds according to the present inventionare valuable starting components for the preparation of polyurethaneplastics, preferably foams. Polyurethane foams prepared from them showgreatly improved fire resistance and excellent mechanical properties.

Accordingly, the present invention also relates to a process for thepreparation of optionally cellular polyurethane plastics comprisingreacting:

(a) polyisocyanates, with

(b) polyhydroxyl compounds; and, optionally,

(c) other compounds containing isocyanate-reactive groups; optionally inthe presence of

(d) blowing agents, catalysts and other known additives;

wherein the polyols according to the present invention which aremodified by acyl urea groups are used as component (b).

Suitable isocyanates include any of the above-mentioned diisocyanatesand also the distillation residues containing isocyanate groups obtainedin the commercial production of isocyanates, optionally in solution inone or more monomeric polyisocyanates, as well aspolyphenyl-polymethylene polyisocyanates of the type obtained bycondensing aniline with formaldehyde, followed by phosgenation. Inaddition to the polyhydroxyl compounds of the present invention, it isalso possible to use the above-mentioned unmodified polyols and theconventional diamine chain-extending agents.

Aliphatic diamines suitable for use in accordance with the presentinvention include, for example, ethylene diamine; 1,4-tetramethylenediamine; 1,11-undecamethylene diamine; 1,12-dodecamethylene diamine andmixtures thereof; 1-amino-3,3,5-trimethyl-5-aminomethyl cyclohexane;2,4- and 2,6-hexahydrotolylene diamine and mixtures thereof;perhydro-2,4'- and -4,4'-diamino-diphenyl methane; p-xylylene diamine;bis-(3-aminopropyl)-methylamine, etc. According to the presentinvention, it is also possible to use hydrazine and substitutedhydrazines, for example methyl hydrazine, N,N'-dimethyl hydrazine andhomologues thereof. Also suitable are acid dihydrazides such ascarbodihydrazide, oxalic acid dihydrazide, the dihydrazides of malonicacid, succinic acid, glutaric acid, adipic acid, β-methyl adipic acid,sebacic acid, hydracrylic acid and terephthalic acid,semicarbazido-alkylene-hydrazides, such as β-semicarbazidopropionic acidhydrazide (DOS No. 1,770,591), semicarbazidoalkylene carbazinic esters,such as 2-semicarbazidoethyl carbazinic ester (DOS No. 1,918,504) oreven aminosemicarbazide compounds, such as β-aminoethylsemicarbazidocarbonate (DOS No. 1,902,931).

Examples of aromatic diamines are bis-anthranilic acid esters accordingto German Offenlegungsschriften Nos. 2,040,644 and 2,160,590; 3,5- and2,4-diaminobenzoic acid esters according to DOS No. 2,025,900; thediamines containing ester groups described in GermanOffenlegungsschriften Nos. 1,803,635; 2,040,650 and 2,160,589;3,3'-dichloro-4,4'-diaminodiphenyl methane; tolylene diamine;4,4'-diaminodiphenyl methane; and 4,4'-diaminodiphenyl disulphide.

According to the present invention, other suitable chain-extendersinclude compounds such as 1-mercapto-3-aminopropane; optionallysubstituted amino acids such as glycine, alanine, valine, serine andlycine; and optionally substituted dicarboxylic acids such as succinicacid, adipic acid, phthalic acid, 4-hydroxyphthalic acid and4-aminophthalic acid.

It is also possible to use compounds which are mono-functional withrespect to isocyanates in proportions of from 0.01 to 10%, by weight,based on the polyurethane solids, as so-called "chain-terminators". Suchmonofunctional compounds are, for example, monoamines, such as butyl-and dibutyl-amine, octylamine, stearylamine, N-methylstearylamine,pyrrolidine, piperidine and cyclohexylamine, monohydric alcohols, suchas butanol, 2-ethyl hexanol, octanol, dodecanol, the various amylalcohols, cyclohexanol, ethylene glycol monoethyl ether, etc.

According to the present invention water and/or readily volatile organicsubstances may be used as blowing agents. Suitable organic blowingagents include acetone, ethyl acetate; halogen-substituted alkanes suchas methylene chloride, chloroform, ethylidene chloride, vinylidenechloride, monofluorotrichloromethane, chlorodifluoromethane,dichlorodifluoromethane; and butane, hexane, heptane or diethyl ether. Ablowing effect may also be obtained by adding compounds which decomposeat temperatures above room temperature giving off gases, such asnitrogen, for example azo-compounds, such as azoisobutyronitrile. Otherexamples of blowing agents and information on the use of blowing agentsmay be found in Kunststoff-Handbach, Vol. VII, by Vieweg and Hochtlen,Carl-Hanser-Verlag, Munich 1966, for example on pages 108 and 109, 453to 455 and 507 to 510.

According to the present invention, catalysts are also frequently used.Examples of suitable known catalysts include tertiary amines, such astriethylamine, tributylamine, N-methyl morpholine, N-ethyl morpholine,N-cocomorpholine, N,N,N',N'-tetramethyl ethylene diamine,1,4-diazabicyclo-(2,2,2)-octane, N-methyl-N'-dimethylaminoethylpiperazine, N,N-dimethyl benzylamine,bis-(N,N-diethylaminoethyl)-adipate, N,N-diethyl benzylamine,pentamethyl diethylene triamine, N,N-dimethyl cyclohexylamine,N,N,N',N'-tetramethyl-1,3-butane diamine,N,N-dimethyl-β-phenylethylamine, 1,2-dimethylimidazole and2-methylimidazole. Other suitable catalysts are known Mannich bases ofsecondary amines, such as dimethylamine, and aldehydes, preferablyformaldehyde, or ketones, such as acetone, methylethyl ketone orcyclohexanone, and phenols, such as phenol, nonylphenol or bisphenol.

Examples of tertiary amine catalysts containing isocyanate-reactivehydrogen atoms include; triethanolamine, triisopropanol-amine, N-methyldiethanolamine, N-ethyl diethanolamine, N,N-dimethyl ethanolamine andthe reaction products thereof with alkylene oxides, such as propyleneoxide and/or ethylene oxide.

Other suitable catalysts are silaamines having carbon-silicon bonds ofthe type described, for example, in German Pat. No. 1,229,290(corresponding to U.S. Pat. No. 3,620,984). These include compounds suchas 2,2,4-trimethyl-2-silamorpholine and 1,3-diethyl aminomethyltetramethyl disiloxane.

Other suitable catalysts are nitrogen-containing bases, such astetraalkyl ammonium hydroxides; alkali metal hydroxides, such as sodiumhydroxide; alkali metal phenolates, such as sodium phenolate; and alkalimetal alcoholates, such as sodium methylate. Hexahydrotriazines may alsobe used as catalysts.

According to the present invention, organometallic compounds, especiallyorgano-tin compounds, may also be used as catalysts.

Preferred organo-tin compounds are tin(II)salts of carboxylic acids,such as tin(II)acetate, tin(II)octoate, tin(II)ethyl hexoate andtin(II)laurate, and the tin(IV compounds, such as dibutyl tin oxide,dibutyl tin dichloride, dibutyl tin diacetate, dibutyl tin dilaurate,dibutyl tin maleate or dioctyl tin diacetate. It is, of course, possibleto use the above-mentioned catalysts in the form of mixtures.

Further representatives of catalysts suitable for use in accordance withthe present invention and details on the way in which the catalysts workmay be found in Kunststoff-Handbach, Vol. VII, by Vieweg and Hochtlen,Carl-Hanser-Verlag, Munich, 1966, for example on pages 96 to 102.

The catalysts are generally used in quantities of from about 0.001 to10%, by weight, based on the quantity of compounds containing at leasttwo isocyanate-reactive hydrogen atoms and having a molecular weight offrom 400 to 10,000.

According to the present invention, surface-active additives, such asemulsifiers and foam stabilizers, may also be used. Examples ofemulsifiers are the sodium salts of castor oil sulphonates or salts offatty acids with amines, such as diethyl amine/oleic acid ordiethanolamine/stearic acid. Alkali metal or ammonium salts of sulphonicacids, such as those of dodecyl benzene sulphonic acid or dinaphthylmethane disulphonic acid, or of fatty acids, such as ricinoleic acid, orof polymeric fatty acids, may also be used as surface-active additives.

Particularly suitable foam stabilizers are polyether siloxanes,especially water-soluble types. These compounds generally have astructure in which a copolymer of ethylene oxide and propylene oxide isattached to a polydimethyl siloxane radical. Foam stabilizers of thistype are described, for example, in U.S. Pat. Nos. 2,834,748; 2,917,480and 3,629,308.

According to the present invention, it is also possible to use reactionretarders, for example substances which are acid in reaction, such ashydrochloric acid or organic acid halides; known cell regulators, suchas paraffins or fatty alcohols or dimethyl polysiloxanes; pigments ordyes; known flameproofing agents, for example trischlorethyl phosphate,tricresyl phosphate or ammonium phosphate and polyphosphate; stabilizersagainst the effects of ageing and weathering; plasticizers; substanceshaving fungistatic and bacteriostatic effects; and fillers such asbarium sulphate, kieselguhr, carbon black or prepared chalk.

Other examples of the surface-active additives and foam stabilizersoptionally used in accordance with the present invention and of cellregulators, reaction retarders, stabilizers, flameproofing substances,plasticizers, dyes and fillers, substances having fungistatic andbacteriostatic effects and also details on the way in which theseadditives are to be used and how they work, may be found inKunststoff-Handbuch, Vol. VII, published by Vieweg and Hochtlen,Carl-Hanser-Verlag, Munich, 1966, for example on pages 103 to 113.

According to the present invention, the reaction components may bereacted by the known one-shot process, by the prepolymer process or bythe semi-prepolymer process, in many cases using machines of the typedescribed, for example, in U.S. Pat. No. 2,764,565. Particulars ofprocessing equipment suitable for use in accordance with the presentinvention may be found, for example, on pages 121 and 205 ofKunststoff-Handbuch, Vol. VII, published by Vieweg and Hochtlen,Carl-Hanser-Verlag, Munich 1966.

In the production of foams, the foaming reaction is preferably carriedout in molds in accordance with the present invention. To this end, thereaction mixture is introduced into a mold. Suitable mold materials aremetals, for example aluminum, or plastics, for example epoxide resins.Inside the mold, the foamable reaction mixture foams and forms themolding. In-mold foaming may be carried out in such a way that themolding has a cellular structure at its surface, or even in such a waythat the molding has a compact skin and a cellular core. According tothe present invention, it is possible in this connection to introducesuch a quantity of foamable reaction mixture into the mold that the foamformed just fills the mold. However, it is also possible to introduceinto the mold more foamable reaction mixture than is required forfilling the mold with foam. This technique is known as "overcharging"and is known, for example, from U.S. Pat. Nos. 3,178,490 and 3,182,104.

Known "external release agents", such as silicone oils, are frequentlyused for in-mold foaming. However, it is also possible to use so-called"internal release agents", optionally in admixture with external releaseagents, such as are known, for example, from German OffenlegungschriftenNos. 2,121,670 and 2,307,589.

According to the present invention, cold-hardening foams may also beproduced (cf. British Pat. No. 1,162,517, German Offenlegungsschrift No.2,153,086).

However, it is, of course, also possible to produce foams by blockfoaming or by the known laminator process.

EXAMPLES EXAMPLE 1

2400 g (0.5 mol) of a polyether of trimethylol propane, propylene oxideand ethylene oxide having an OH-number of 35 are dehydrated by heatingto 120° C. in a vacuum of 12 Torr and then combined, at 120° C., with 76g (0.25 mol) of bis-(3-isocyanato-4-methylphenyl)-carbodiimide dissolvedin 300 ml of xylene.

After all the isocyanate groups have reacted, which takes about 2 hours,18 g (0.3 mol) of acetic acid are added at 80° C. Following removal ofthe solvent (at from 90° to 100° C./0.15 Torr), the product whichcontains acyl urea groups has a viscosity η₂₄ of 7400 cP and anOH-number of 24 (molecular weight approximately 10,000).

EXAMPLE 2

172 g (0.1 mol) of a polyester of adipic acid, 1,6-hexane diol andneopentyl glycol having an OH-number of 66 are dried by heating to 120°C. in a vacuum of 12 Torr and subsequently combined with 15.2 g (0.05mol) of bis-(3-isocyanato-4-methylphenyl)-carbodiimide. After theisocyanate groups have reacted at from 110° to 120° C., 3 g (0.05 mol)of acetic acid are added at from 80° to 90° C. The carbodiimide groupsreact to form acyl urea groups. The reaction product has a viscosity η₂₄of 9280 cP and an OH-number of 30 (molecular weight approximately 4000).

EXAMPLE 3

2400 g (0.5 mol) of a polyether of trimethylol propane, propylene oxideand ethylene oxide having an OH-number of 35 are dehydrated over aperiod of 30 minutes at 120° C. in a vacuum of 12 Torr and issubsequently combined, at 120° C., with 76 g (0.25 mol) ofbis-(3-isocyanato-4-methylphenyl)-carbodiimide.

After the isocyanate groups have reacted, 50 g (0.25 mol) of lauric acidare stirred in at from 80° to 90° C., the carbodiimide groups reactingto form the corresponding acyl urea groups. The product has a viscosityat 24° C. of 7200 cP and an OH-number of 24 (molecular weightapproximately 10,000).

EXAMPLE 4

480 g (0.1 mol) of a polyether of trimethylol propane, propylene oxideand ethylene oxide having an OH-number of 35 are dried by heating for 30minutes to 120° C. in a vacuum of 12 Torr and subsequently reacted with15.2 g (0.05 mol) of bis-(3-isocyanato-4-methylphenyl)-carbodiimide.

After the isocyanate groups had reacted at from 110° to 120° C., 3.6 g(0.05 mol) of acrylic acid are added at from 80° to 90° C. Thepolyhydroxy polyether formed, which is modified with acryloyl ureagroups, has a viscosity η₂₄ of 8520 cP and an OH-number of 24 (molecularweight approximately 10,000) after thin-layer distillation at from 90°to 100° C./0.15 Torr.

EXAMPLE 5

2400 g (0.5 mol) of a polyether of trimethylol propane, propylene oxideand ethylene oxide having an OH-number of 35 are dehydrated by heatingto 120° C. in a vacuum of 12 Torr and subsequently combined, at 120° C.,with 76 g (0.25 mol) of bis-(3-isocyanato-4-methylphenyl)-carbodiimide.After all the isocyanate groups have reacted, which takes about 2 hours,21.5 g (0.25 mol) of methacrylic acid are added. The product whichcontains methacryloyl urea groups has a viscosity at 24° C. of 13320 cPand an OH-number of 23 (molecular weight approximately 10,000).

EXAMPLE 6

200 g (0.1 mol) of a polypropylene glycol having an OH-number of 56 aredehydrated for 30 minutes at 120° C. in a vacuum of 12 Torr. 15.2 g(0.05 mol) of bis-(3-isocyanato-4-methylphenyl)-carbodiimide are thenadded at from 110° to 120° C.

After the isocyanate groups have reacted, 5.05 g (0.025 mol) of sebacicacid are stirred in at from 80° to 90° C. The polyhydroxy polyethermodified with acyl urea groups has a viscosity η₂₄ of 34400 cP(molecular weight approximately 9000).

EXAMPLE 7

480 g (0.1 mol) of a polyether of trimethylol propane, propylene oxideand ethylene oxide having an OH-number of 35 are dehydrated for 30minutes at 120° C./12 Torr and subsequently reacted with 15.2 g (0.05mol) of bis-(3-isocyanato-4-methylphenyl)-carbodiimide.

After the isocyanate groups have reacted at from 110° to 120° C., 1.5 g(0.025 mol) of acetic acid are stirred in at from 80° to 90° C.Thereafter, the product still shows a strong carbodiimide band in itsIR-spectrum. The remaining carbodiimide bands are converted intoguanidine groups by introducing 1.1 g (0.025 mol) of dimethylamine. Thepale reddish product formed has a viscosity η₂₄ of 7400 cP (molecularweight approximately 10,000).

EXAMPLE 8

100 g (0.4 mol) of 4,4'-diisocyanatodiphenyl methane dissolved in 100 gof xylene are subjected to carbodiimide formation at 120° C. in thepresence of 8 g of the insoluble catalyst containing phosphine oxidegroups according to Example 1a of DOS No. 2,552,350 until 3.5 liters ofcarbon dioxide have formed. The catalyst is separated off by filtrationand 70 g (0.2 equivalents of isocyanate groups, as determined bytitration) of the filtrate are reacted with 400 g (0.2 mol) of apolypropylene glycol having an OH-number of 56 which was dried byheating to 120° C./12 Torr.

After the isocyanate groups have reacted at from 110° to 120° C., thereaction mixture is cooled to from 80° to 90° C. and 3.2 g (0.055 mol)of acetic acid are added. Following removal of the solvent, thepolyhydroxy polyether formed, which is modified with acyl urea groups,has a viscosity η₂₄ of 8730 cP and an OH-number of 28 (molecular weightapproximately 4600).

EXAMPLE 9

200 g (0.1 mol) of a polypropylene glycol having an OH-number of 56 aredehydrated at 120° C. in a vacuum of 12 Torr and reacted with 15.2 g(0.05 mol) of bis-(3-isocyanato-4-methylphenyl)-carbodiimide.

After the isocyanate groups have reacted at from 110° to 120° C., 10.1 g(0.05 mol) of sebacic acid are stirred in at from 80° to 90° C. Thepolyhydroxy polyether which is modified both with acyl urea groups andalso with carboxyl groups has a viscosity η₂₄ of 39800 cP and an acidnumber of 15.

EXAMPLE 10

111 g (0.5 mol) of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane are subjected to carbodiimide formation at 150° C. in thepresence of 0.3 ml of a mixture of1-methyl-1-phospha-2-cyclopentene-1-oxide and1-methyl-1-phospha-3-cyclopentene-1-oxide until 6 liters of carbondioxide have formed.

20 g. (0.05 mol) of the reaction product are reacted with 200 g (0.1mol) of a polypropylene glycol having an OH-number of 56 which has driedby heating to 120° C. in a vacuum of 12 Torr.

After the isocyanate groups have reacted at from 110° to 120° C., thereaction mixture is cooled to from 80° to 90° C. and 8 g (0.05 mol) ofN,N-dimethyl-6-aminocaproic acid are added. The polyhydroxy polyetherformed, which is modified with acyl urea groups, has a viscosity η₂₄ of10700 and an OH-number of 26 (molecular weight approximately 4600).

EXAMPLE 11

15.2 g (0.2 mol) of 1,2-propane diol dissolved in 60 ml of N,N-dimethylformamide are reacted at 80° C. with 30.4 g (0.1 mol) ofbis-(3-isocyanato-4-methylphenyl)-carbodiimide dissolved in 250 ml oftoluene.

After the isocyanate groups have reacted, 6.6 g (0.11 mol) of aceticacid are added at from 80° to 90° C. and the solvent is subsequentlyremoved. A product containing acetyloyl groups and having a meltingpoint of 85° C. is obtained.

EXAMPLE 12

172 g (0.1 mol) of a polyester of adipic acid, 1,6-hexane diol andneopentyl glycol having an OH-number of 66 are dried by heating to 120°C. in a vacuum of 12 Torr and subsequently mixed with 15.2 g (0.05 mol)of bis-(3-isocyanato-4-methylphenyl)-carbodiimide. After the isocyanategroups have reacted at from 110° to 120° C., 3.3 g of acetic acid areadded at 80° C. A wax-like polyol containing acetyloyl groups isobtained (molecular weight approximately 3800).

EXAMPLE 13

200 g (0.1 mol) of a polyether of propylene glycol and propylene oxidehaving an OH-number of 56 are dehydrated by heating to 120° C. in avacuum of 12 Torr and subsequently reacted at 120° C., with 15.2 g (0.05mol) of bis-(3-isocyanato-4-methylphenyl)-carbodiimide. After all theisocyanate groups have reacted, which takes about 2 hours, 3.8 g (0.05mol) of thioacetic acid are added at 120° C. The polyol formed, which ismodified with acetyloyl thiourea groups, has a viscosity η₂₄ of 2050 cP(molecular weight approximately 4400).

What is claimed is:
 1. Compounds containing at least two terminalhydroxyl groups and having a molecular weight of from 400 to 20,000which compounds comprise segments in their molecular structurecorresponding to the following general formulae: ##STR5## wherein X andY, which may be the same or different, each represents oxygen orsulphur;R¹ represents hydrogen or a monofunctional or--in the form of abridge to further acyl groups--a di- or trifunctional C₁ -C₁₈ aliphatic,C₄ -C₁₅ cycloaliphatic, C₆ -C₁₅ araliphatic or aromatic radical whichmay contain one or two double bonds and/or be branched and which mayoptionally contain one or two substituents selected from the groupconsisting of hydroxyl, mercapto, secondary amino, sulphonic acid ester,phosphonic acid ester, carboxylic ester, siloxane or trifluoromethylgroups, fluorine, chlorine, bromine or iodine; R² represents adifunctional aliphatic, cycloaliphatic, aromatic or araliphatic radicalcontaining from 4 to 25 carbon atoms obtained by removing the isocyanategroups from a diisocyanate; A represents an n-functional radicalobtained by removing the hydroxyl groups from a polyhydroxyl compoundhaving a molecular weight of from 62 to 6000; n represents an integer offrom 2 to 8; and z represents an integer having a value of from 0 to(n-1).
 2. The compounds of claim 1 whereinX and Y are oxygen R¹represents C₁ -C₁₇ aliphatic hydrocarbon radical which may optionallycontain double bonds and/or branches and which may be substituted bychlorine, hydroxyl groups or secondary alkylamino groups; and n is aninteger from 2 to
 4. 3. The compounds of claim 1 wherein thediisocyanate from which the NCO group is removed to form R² is of thetype in which one isocyanate group has a greater tendency towardcarbodiimide formation than the other.
 4. The compounds of claim 1wherein the polyol from which the hydroxyl group is removed to form A isselected from the group consisting of polypropylene glycols; trimethylolpropane--or glycerol--started copolymers of propylene oxide and ethyleneoxide; and polyesters based on adipic acid and 1,4-butane diol,diethylene glycol, 1,6-hexane diol and/or neopentyl glycol.
 5. Thecompounds of claim 1 wherein R¹ represents a C₁ -C₁₇ aliphatichydrocarbon radical which may optionally contain one or two double bondsand/or be branched and which may be substituted by chlorine, hydroxygroups or secondary alkylamino groups.
 6. A process for preparingpolyhydroxyl compounds containing acyl urea groups and having amolecular weight of from 400 to 20,000, comprising (A) reactingdiisocyanatocarbodiimides corresponding to the following generalformula:

    OCN--(R.sup.2 -N═C═N)--R.sup.2 -NCO

at a temperature of from about 25° to 130° C., optionally in thepresence of an inert solvent, with polyhydroxyl compounds correspondingto the following general formula:

    A--OH).sub.n

in an OH/NCO-ratio of from 1.2:1 to 30:1 to form a polyhydroxyl compoundcontaining carbodiimide groups and (B) completely or partially reactingthe carbodiimide groups remaining in the product of Step (A) at atemperature of from 25° to 100° C., optionally in the presence of aninert solvent, with a carboxylic acid corresponding to the followinggeneral formula: ##STR6## to form acyl urea groups, and (C) distillingoff the inert solvent, if used, wherein m represents a number of from 1to 10; s represents an integer of from 1 to 3; and R¹, r², a, x, y and nare as defined in claim
 1. 7. The process of claim 6 wherein Step (A) iscarried out at a temperature of from 90° to 120° C. and Step (B) at 60°to 90° C.
 8. The process of claim 6 wherein m represents 1 or 2 and srepresents 1 or
 2. 9. The process of claim 6 wherein the OH/NCO ratio inStep (A) is from 1.5:1 to 15:1.
 10. The product of the process of claim6.